A. Field of the Invention
The present invention relates to an image displaying apparatus and image displaying method thereof for applying to an image radiography apparatus, and more particularly to an apparatus and method for displaying two dimensional radiographic images or three dimensional radiographic images of an object (patient) which are acquired through a medical image radiography apparatus and for displaying together with posture data or posture marks for indicating directions of the two dimensional-radiographic images or three dimensional-radiographic images on the same screen of a monitor.
B. Background of the Invention
X-ray diagnosis apparatuses, such as an X-ray CT apparatus and a magnetic resonance imaging apparatus, are used to display radiographic images of body insides of a patient in order to observe states of diseases or injuries. This is very important for deciding a policy of medical treatment or an operation plan. In accordance with developments of recent computer technologies, it becomes possible to display images that are reconstructed in real time based on image data collected through a medical image radiography apparatus on a monitor. It is also possible to display not only two dimensional-images but also three dimensional-images, such as an multi-planer reconstruction (MPR) image on the monitor. Since it becomes possible to easily specify a morbid position, three dimensional-images are useful for deciding an operation plan.
Usually, as illustrated in FIG. 6, an object (patient) 1 is lying on a top plate 3 of a bed apparatus 2, and the image data collection through a medical image radiography apparatus is performed by sliding the top plate 3 to a radiography position in an image radiography apparatus 4 with keeping the object 1 in such a horizontal lying posture. To easily and correctly observe or diagnose a reconstructed image of the acquired image data displayed on a monitor, it needs to display lying posture data or posture indicating marks for the image data that indicate the posture or directions of the object 1 at a radiography time also displayed on the same screen with attached to the reconstructed image.
The characters or marks for indicating the posture data are primarily decided based on the coordinates or the direction cosines of the position of the top plate or the bed apparatus for supporting the object at a time of image radiography. Generally, the coordinates are decided by the irradiation axes (as shown by the X axis and Y axis in FIG. 6) that pass through an irradiation center of the image radiography apparatus and a sliding center axis of the sliding top plate 3 of the bed apparatus (as shown by the Z axis in FIG. 6). Hereinafter, the posture data that is primarily decided by these reference coordinates is referred as a first posture data.
The posture data displayed on a monitor together with a reconstructed image is represented by a state of characters or marks. FIG. 7 explains an example of the posture data that are acquired by placing the top plate 3 supporting an object 1 at a radiation center position of the image radiography apparatus. As an exemplary posture data, a character “A” indicates a front abdomen side of the object 1, a character “P” is a posture data indicating a direction of a back side of the object 1. Similarly, the characters “R” and “L” indicated right and left directions of the image of the object lying on the tap plate, respectively. Further, the characters “H” and “F” (not shown), will be added to indicate posture date for a three dimensional image in order to respectively indicate a head side and a foot side of the object, respectively.
FIG. 8 illustrates an example of a radiographic three-dimensional image 1a of a head portion of an object 1 and posture data displayed around the head portion image 1a on a monitor. The head portion image 1a is reconstructed by an image processing apparatus based on image data that is collected through an image radiography apparatus 4, as e shown in FIG. 6. At a radiography time, posture data of the head portion also acquired through an image radiography apparatus 4 based on coordination of a top plate for supporting an object. The posture data are provided around the image 1a so as to indicate the direction of the image 1a. As the posture data or posture mark, four characters “A”, “R”, “P” and “L” are displayed on a monitor of the image display apparatus. Since various other reference data may also be displayed on a screen of the monitor 5 in addition to the posture data, it is desirable to render displaying items as small as possible in order to easily read a screen. Since either one of a front face or a back face, and either one of right or left are indicated, the other position is automatically understood, it is sufficient to display only two characters or marks for indicating as the posture data on a monitor. Usually, characters “R” and “P” are displayed on the monitor and opposite direction indicating characters “A” and “L” are often omitted.
The displayed posture data provided around a reconstructed image on a monitor is not aimed to indicate a precise angle of an object, but to simply show the directions for the posture of the object. In FIG. 8, a coordinate axis is shown by a dotted line for only using a better understanding of the invention. Accordingly, such a coordinate axis need not be displayed on an actual monitor.
As explained above, the posture data displayed on a monitor 5 together with a reconstructed image is primarily decided based on the coordinates or the directions of a bed apparatus 2 and/or a top plate 3 during radiography of the image. Accordingly, it is desirable to place an object on the plate so as to be placed in a horizontal direction facing toward a perpendicular direction of the plate. However, due to the status of the patient's injury or sickness, the object might not be able to take such a horizontal posture with facing right upward on the top plate. In such a case, it is inevitable to take radiography even though the actual posture of the object 1 is laying at a displaced position different from the coordinates for the bases of the first posture data. Consequently, a displacement may appear between the reconstructed original image and the first posture data displayed on the monitor 5.
FIG. 9 illustrates an example of such a case. Thus, it is impossible for a patient to turn his head towards a perpendicularly top direction, and the head of the patient is placed with tilting around 40 degrees toward a right side of his body that is different from the coordinate axis A based on the irradiation axis of the image radiography apparatus. The image data is acquired at this situation and the original reconstructed image displayed on a monitor screen. When the radiography is executed with displacing a patient's posture from a prescribed coordinate positions, as shown in FIG. 9, an original reconstructed tomography image 1a is displayed with tilting toward the posture data “L”. On the contrary, the display of the first posture data is preliminarily decided with no relation to the actual posture of the object. Accordingly, the reconstructed original image and the first posture data are displayed on the monitor with appearing a displaced relationship between them. Such a displacement between the reconstructed original image and the first posture data causes difficulties of the observation or errors of diagnosis. To avoid such difficulties, one conventional technique has been ignored even though some degree of the displacement is present between the reconstructed original image and the first posture data. Another conventional technique changes a posture data displaying mode from a “normal mode,” in which the posture data is set to be usually displayed, to an “other mode” in which the posture data is disappeared from the monitor screen and the original reconstructed image only has been displayed. However, when the original reconstructed image is observed with attaching no posture data at a radiography time, in particular when a three dimensional image, it may happen that a right and a left direction are misunderstood. To avoid such a misunderstanding, an observer i.e., a doctor, is required to correct the image position in his brain in order to diagnose or to plan an operation. Thus, this places a big burden on the observer, and it also is a cause of an error for diagnosis.